A NEW KNEE JOINT – A NEW LEASE OF LIFE
The aim of this information sheet is to answer questions that may be in your mind about a knee replacement.
Do I need a knee replacement?
“If pain from a worn out knee is bad enough and not responding to tablets then it needs replacing”. The decision to replace a knee will involve weighing up the risks of the operation and the benefit you will get if the operation is done. The longer and the larger doses of pain medication you take, more are the chances of side effects like damage to stomach, kidney etc.
The decision is easy if you are suffering from severe pain and can't walk far, especially if you are older. Most people having a knee replacement are over the age of 50. Putting off the operation if you have severe arthritis could allow the muscles to become weaker, make the knee more stiff and deformed and will reduce the chance of success. If you are under the age of 50 you are highly likely to need a further operation later in life.
What can I expect from a knee replacement?
About 90% of replacement knees last for more than 10 years. However, there are many factors which determine the success of a knee replacement and people's expectations vary greatly. Most people have very little pain after the first 6 months but, even for those who do, it usually improves over two years. Most people are able to walk with little pain for 30 minutes, but a few may need a walking stick. The improvement in walking also helps the heart and lungs and people are generally fitter a year after surgery.
Giving way (jerking) of the knee should get better in 7 out of 8 patients after surgery. 2 out of 3 patients can easily go out for their household shopping. After a knee replacement 4 out of 5 people can use stairs with relative ease. For younger people, a knee replacement will probably not be comfortable enough to get back to heavy manual work. Do not expect your knee to bend fully, especially if it was stiff before.
What is the new joint and how does it work?
The worn out ends of the bones are removed and would be replaced with metal and plastic. These materials have been successfully tried and tested for many years. The end of the thigh bone (femur) is replaced by a single curved piece of metal. The top end of the shin bone (tibia) is replaced by a flat plate of metal. Plastic is fixed to this flat plate to act like cartilage and help the bones move easily. The components of a knee replacement are usually cemented into the bone. It is also possible to correct any 'bow leg' or 'knock knee' deformity of the knee to some extent while putting in the new joint.
About the operation and your stay in the hospital
During the first 24 hours after surgery your pain will be controlled by the drugs or injections. After the first day it is likely that the various plastic tubes for fluids, medication, and drainage will be removed. You will be encouraged to take normal diet. Physiotherapist will help you to start walking. Within a day or two you will be sitting on the side of the bed and you will be encouraged to bend and straighten your knee. If you have had both knees replaced you will be less mobile atfirst. You will be taught exercises of the knee to strengthen the muscles and also to mobilise the knee which in the beginning can be painful.
Everyone is different and some people progress faster than others. If you had good muscles before surgery and your knee is not very bruised, you will be up and about walking using a frame from the first post operative day. But people who are very heavy or who have weak muscles may take a day or two more to walk and to gain proper control of the knee. This is especially likely if you have rheumatoid arthritis. Some patients are a little too over-enthusiastic and cause more bruising by being too active. Then you may be advised to slow down a little! The main priority is to make sure that the wound heals properly in the first two weeks.
It is very likely that you will be able to walk along the corridor without help, just using a frame or crutches for support. If everything is well you will be able to go home in about 5 days. You will need to see the doctor at the end of second week for wound check and suture removal.
The first few weeks at home
You may need painkillers because exercise can be painful. You need to carry out exercises to build up the muscles and recover the range of movement. Good supportive outdoor shoes (not slippers) are best worn in the early days to help your walking.
About 6 weeks after the operation it is likely that you will be seen again in the clinic. If you were using one stick before the operation, you will probably no longer need it. If you were using two sticks or a frame you will probably now only need one stick. You will probably be able to go out from your home independently 6 weeks after surgery and return to light office work. If your work involves a lot of standing and some light lifting you will not be ready until about three months after surgery.
What are the main risks of the operation?
Total knee replacement is a major operation which by and large is a safe surgery but has risks like any other major operation. There are the risks of complications at the knee joint itself. For example, in 1 in 10 patients the healing of the wound takes longer than normal, requiring dressings and possibly an extra week in hospital. Or, a wound infection may occur, requiring antibiotics, but a deep wound infection is very rare. However, if a deep wound infection happened it might need further 'revision' surgery and very occasionally the new knee joint will need to be removed altogether.
There are also the general risks of having a major operation. Most people come through surgery without a problem and the risks of a stroke, a heart attack or death are very low (the risk of death is less than 1 in 100) following a total knee replacement.
Stiffness: Sometimes the knee becomes very stiff in the weeks after the operation for no apparent reason. The harder you try to exercise the knee, the stiffer and more painful it becomes. A few days without exercises - just resting the knee - may make all the difference. Occasionally, if your knee is not progressing well at about 6 weeks, your surgeon may feel it best to 'manipulate' your knee. However, you need to have realistic expectations. If you had a knee that was very stiff before surgery, you are not likely to be fully mobile after knee replacement.
Can an artificial knee be replaced with another one?
Yes, it can. If a replaced knee wears out (this will usually be after more than ten years) then it can be replaced with another replacement- a 'revision' operation, and this is difficult than the first. However many patients have had successful revision surgeries and some have had three or more replacement joints.
Finally, it is needless to say that these joint replacement surgeries have transformed the lives of patients who otherwise would have remained crippled and forced to lead an indoor life with detrimental effect on general health and well being of a patient and a burden on the family.